How to Pronounce S and ES Endings: /s/, /z/ and /ɪz/

Why do S and ES endings have three pronunciations?

The suffix -s represents several grammatical endings, but speech adapts it to the preceding sound. Linguists call the spoken forms allomorphs: alternative pronunciations of the same grammatical unit. Here, the regular ending is /s/, /z/ or /ɪz/.

The pattern is not random. A voiceless final sound is followed by voiceless /s/, a voiced final sound by voiced /z/, and a word that already ends in a sibilant needs a short extra vowel so that the two similar sounds can be heard separately.

When is the S ending pronounced /s/?

Pronounce the ending /s/ after a voiceless non-sibilant. The most useful final sounds to remember are /p, t, k, f, θ/. Your vocal folds are not vibrating at the end of the base word, so the ending also remains voiceless.

Join the two consonants directly. Cats ends /ts/, not /tɪs/, and books ends /ks/, not /kɪs/. Avoid inserting an extra vowel unless the base word ends in a sibilant.

When is the S ending pronounced /z/?

Pronounce the ending /z/ after a voiced non-sibilant or any vowel sound. Useful voiced final consonants include /b, d, ɡ, v, ð, m, n, ŋ, l, r/. The voice continues through the ending instead of switching off.

Notice that the letter is still written s, but the spoken ending is /z/. This is a good example of why English spelling cannot always tell you the pronunciation directly. IPA makes the final sound visible.

When is the ES ending pronounced /ɪz/?

Use /ɪz/ after a sibilant: /s, z, ʃ, ʒ, tʃ, dʒ/. These sounds already have a strong hissing, buzzing or shushing quality. Adding only /s/ or /z/ would make the boundary difficult to hear, so English inserts a short vowel and creates another syllable.

Count the syllables to check the pattern: bus has one syllable, while buses has two. Watch has one; watches has two. Some phonetic descriptions write this weak vowel as /ə/. This guide uses the learner-dictionary convention /ɪz/ consistently.

How can you hear voiced and voiceless sounds?

Voiceless sounds such as /p, t, k, f, θ, s/ do not use vocal-fold vibration; voiced sounds such as /b, d, ɡ, v, ð, z, m, n, ŋ, l, r/ and vowels do. Place two fingers lightly on your throat and alternate /ssss/ and /zzzz/. Vibration should be more noticeable for /z/. Treat this as a simple learner cue, not a scientific measurement.

Now say the base word without its ending. If the final sound is /t/ in cat, the throat is not vibrating and the added ending is /s/. If it is /ɡ/ in dog, vibration continues into /z/. The same voicing idea also helps distinguish the English /θ/ and /ð/ TH sounds.

What is a sibilant?

A sibilant is a consonant with prominent high-frequency friction: a hiss, buzz or shush. For this ending rule, the relevant sounds are /s/ in bus, /z/ in rose, /ʃ/ in dish, /ʒ/, /tʃ/ in watch and /dʒ/ in judge.

Learn the audible groups—S/Z, SH, CH and J—and remember that a sibilant takes /ɪz/. Check this category first because voiced and voiceless sibilants use the same ending.

Should you follow spelling or pronunciation?

Follow the final sound. English letters and sounds do not have a one-to-one relationship, so the final letter may lead you to the wrong rule. Laugh ends with the letters gh but the sound /f/, so laughs ends /fs/. Play ends in the vowel /eɪ/, so plays ends in /z/. Watch ends in /tʃ/, so watches adds /ɪz/.

Remove the written ending, say the base word aloud, and listen to what remains. If the spelling still distracts you, check the word in IPA. The guide to English spelling, pronunciation and IPA explains why this approach is more reliable than guessing from letters.

Where are the three endings used?

The same pronunciation pattern appears in several common grammatical forms:

• Regular noun plurals: one cat, two cats; one dog, two dogs; one bus, two buses.
• Third-person singular verbs: she works; he runs; it matches.
• Possessive endings: Jack’s /s/, Sam’s /z/ and George’s /ɪz/.

The rule applies to a regular S or ES suffix. It does not explain an irregular plural such as children or an unrelated s already inside a base word. Written conventions vary in some possessive names, but the spoken ending still follows the sound pattern.

Why is works /s/, runs /z/ and watches /ɪz/?

Works ends in /s/ because the base verb work ends in voiceless /k/. Runs ends in /z/ because run ends in voiced /n/. Watches ends in /ɪz/ because watch ends in the sibilant /tʃ/.

The grammar is the same in all three examples: each verb has a third-person singular ending. The pronunciation changes only because the last sound of the base verb changes.

A simple S and ES pronunciation decision tree

1. Remove the suffix and say the base word. For watches, begin with watch.
2. Does the base end in a sibilant? If it ends in /s, z, ʃ, ʒ, tʃ, dʒ/, choose /ɪz/ and stop.
3. If not, is the final sound voiceless? After /p, t, k, f, θ/, choose /s/.
4. Otherwise, choose /z/. This covers vowels and voiced non-sibilant consonants.

Fast rule: sibilant → /ɪz/; otherwise voiceless → /s/; otherwise → /z/.

Common pronunciation errors

Pronouncing every written S as /s/ or devoicing /z/

This can affect dogs or names. Keep the voice running through the final /z/.

Adding /ɪz/ after every consonant

An extra vowel changes the syllable count: cats should not become “cat-is.” Reserve the added syllable for a base word that ends in a sibilant.

Dropping a difficult final cluster

Words such as books and works end with two or more consonant sounds. Practice the base word first, hold the final consonant briefly, then add the suffix without separating them with a vowel.

Following the final letter instead of the final sound

Silent letters and alternative spellings make this unreliable. Say or look up the base word first, then apply the decision tree.

Overemphasizing the ending

Keep the suffix audible, but integrate it into the whole word rather than making it unnaturally long or strong.

Listen for the three endings

Use clear model audio and listen only to the final transition. The ending should attach smoothly to the base word. Focused listening practice can help you hold attention on that short final segment.

Swipe horizontally to see the full table on a small screen.

First contrast cats–dogs–buses. Then use books–names–dishes and cups–boys–watches. This forces you to change the ending deliberately instead of repeating one pattern automatically.

How to practice S and ES endings

1. Choose one base word. Say it without the ending and identify its final sound.
2. Classify the sound. Check sibilant first, then voiceless; use voiced as the remaining category.
3. Add the ending slowly. Join cat + /s/, dog + /z/ or bus + /ɪz/ without changing the base.
4. Check voicing or syllables. Use the throat test for /s/ and /z/; count syllables for /ɪz/.
5. Record and compare. Listen for the final sound rather than judging the whole word at once.
6. Move into a short phrase. Try two cats, the dogs run and she watches films.
7. Mix the categories. Read a short list containing all three endings and explain each choice.

Apply the full chain: dog → final /ɡ/ → voiced → /z/ → dogs → two dogs. Repeat it briefly with cat → cats → two cats and bus → buses → two buses.

Keep the practice narrow. If /z/ is consistently devoiced, work with voiced endings only. If clusters are difficult, compare the base and inflected forms and build speed gradually. Use a short pronunciation drill, then record yourself for focused review.

Are the rules different in British and American English?

The three-way suffix rule is the same in standard British and American reference pronunciations. Cambridge lists /-s/, /-z/ and /-ɪz/ for both UK and US English.

The base word may differ between accents, which can change the full IPA transcription without changing the decision process. For example, British and American vowels can differ in dogs or watches, but the final consonants still lead to /z/ and /ɪz/. Choose one model for production practice and listen to both for comprehension.

How Speakometer helps you practice word endings

Speakometer combines automatic pronunciation feedback with sound-level teaching and targeted practice. For S and ES endings, it helps learners see whether the written ending is pronounced /s/, /z/ or /ɪz/, hear the relevant sound and practice the pattern in additional words.

1. Start with the dedicated S and ES endings course. Practice and compare words ending in /s/, /z/ and /ɪz/ with the selected British RP or General American model.
2. Review color-coded IPA feedback. Speakometer analyzes the attempt at sound level and highlights individual IPA sounds. Automatic feedback is useful guidance rather than an infallible diagnosis.
3. See which final sound the word uses. IPA makes the sound represented by the written ending visible as /s/, /z/ or /ɪz/.
4. Tap an individual IPA sound. The sounds in the feedback are interactive, so learners can tap the final sound and hear its reference in isolation.
5. Open the sound formation guide. Original articulation illustrations, step-by-step mouth and tongue-position guidance, model audio, spelling patterns and example words help explain how an individual English sound is produced and written.
6. Compare related sounds. Use targeted sound contrasts when a final /z/ becomes /s/, or when another sound is substituted. Speakometer includes more than 8,000 minimal pairs and sound contrasts.
7. Practice the ending across more words. Search a library of more than 65,000 words to test the same ending after different final sounds and in different grammatical forms.
8. Replay your recording and retest. Compare your recorded voice with the selected model, make one focused change and try the word again.

Speakometer connects the written ending to the sound it actually represents: identify /s/, /z/ or /ɪz/ in IPA, hear the sound, compare related sounds, practice more words and retest.

Frequently asked questions

What are the three pronunciations of an S or ES ending?

They are /s/, /z/ and /ɪz/. The final sound of the base word determines which one is used.

When do I pronounce the ending /s/?

Use /s/ after a voiceless non-sibilant sound such as /p, t, k, f, θ/: cups, cats, books and cliffs.

When do I pronounce the ending /z/?

Use /z/ after a voiced non-sibilant consonant or a vowel: dogs, names, calls and boys.

When does ES add another syllable?

It adds the /ɪz/ syllable after a sibilant such as /s, z, ʃ, ʒ, tʃ, dʒ/: buses, roses, dishes, watches and judges.

Why does the S in dogs sound like Z?

Dog ends in voiced /ɡ/, so voicing continues into the suffix and produces /z/.

Do plural nouns and third-person verbs use the same rule?

Yes. Regular noun plurals and third-person singular verb endings use the same three-way pronunciation pattern. Possessive S endings follow it too.

Should I use spelling to choose the ending?

No. Use the final sound of the base word. Spelling helps show that a suffix is present, but it does not reliably tell you whether the spoken ending is /s/, /z/ or /ɪz/.

Sources and further reading

The three UK and US suffix pronunciations were checked against Cambridge Dictionary’s entry for -s pronunciation. The plural spelling and /ɪz/ guidance follows Cambridge Grammar’s references for regular noun forms and regular verb -s forms.

The final-sound, voicing and allomorph explanations were checked against the University of Sheffield’s Sounds of English guide and Northern Virginia Community College’s open chapter on allomorphy. The possessive examples follow Cambridge Grammar’s possessive S pronunciation guidance.

Conclusion

To pronounce an English S or ES ending, say the base word and identify its final sound. Choose /ɪz/ after a sibilant, /s/ after another voiceless sound, and /z/ in the remaining voiced environments. Practice the contrast in complete words, check voicing and syllable count, then move the words into phrases and sentences.